Field of the Invention
The present invention relates to an information processing system for controlling a movable unit including a movable portion capable of changing an position and a orientation and a method, a program, and a computer-readable storage medium therefor.
Description of the Related Art
With recent progress in robot technology, robots are beginning to perform complicated tasks, instead of people, which had been performed by people in the past such as assembling of industrial products. Such robot performs an assembling process by picking up a component using an end effector such as a hand.
In the past, components which are to be picked up are supplied by utilizing an apparatus, which is called a parts feeder, for supplying components by arranging each of the components one by one or by stacking components in a pallet (a box) in various orientations. When a part feeder is used, each of the components is supplied in such a manner that the position and the orientation of each of the components are determined in advance, and therefore, a robot can relatively easily pick up the components. However, preparing a parts feeder apparatus requires an additional cost. Moreover, in some cases, it may be necessary to prepare different parts feeders which are suitable for shapes of the components. On the other hand, when the components are supplied as being stacked, the components are simply placed on a pallet, and this can avoid the increase of the cost. Further, in response to the tendency of wide-variety and small-lot production in recent years, the method for supplying components in a stacked manner, which can cope with various types of components in a short time, attracts attention.
For example, as a technique about picking of a stacked component using a robot and image sensors, the publication of Japanese Patent No. 3556589 discusses a method for picking up a component using a combination of operations of a plurality of sensors and a robot.
When a stacked component is picked up accurately, it is necessary to correct a relative positional relationship with the component before the position where the component is grabbed. This is because an operation accuracy of a multi-axial robot with absolute position designation is low, and occlusion may occur in which one of the sensors cannot observe the component, and thus, the accuracy at the position where the component is grabbed cannot be ensured. Therefore, it is necessary to observe the component at the position where the robot grabs the component.
In the publication of Japanese Patent No. 3556589, a sensor for obtaining three dimension includes an apparatus for emitting a pattern onto a housing to ensure a baseline and an apparatus for capturing an image, and accordingly, the sensor is large and its weight is heavy. Therefore, the weight of the sensor is added to a load capacity of an arm portion of the robot, and increases the inertia during movement. As a result, a robot with a higher degree of rigidity is required, which increases the cost.